One type of semiconductor package is a multi-chip semiconductor package or multi-chip package (MCP), which is an electronic package with multiple components—e.g., integrated circuits (ICs), semiconductor dies or other discrete components—that are packaged onto a substrate. MCPs can be formed using three-dimensional (3D) packaging technologies that exploit the z-height dimension by stacking semiconductor dies in a vertical configuration to make the resultant MCP footprint in the x-y dimensions smaller. Examples of packages created by 3D packaging technologies include package-on-package (PoP) solutions, package-in-package (PiP) solutions, embedded wafer level (eWLB) packages, etc.
Integrated heat spreader (IHS) solutions can be used in MCPs to dissipate unwanted heat produced by the components of MCPs. One disadvantage of stacking dies in an MCP is that the z-height of components in the MCP can vary, which can have negative effects on the performance capabilities of the MCP by increasing unwanted heat production. Typical integrated heat spreader (IHS) solutions do not work as effectively because of these variations in component height. FIGS. 1A-1B illustrate this issue.
FIG. 1A is a cross-sectional view of a typical MCP 100 that includes a typical IHS solution. As shown in FIG. 1A, components 103 and 104, each of which can include semiconductor die(s), are on a substrate 101. In the MCP 100, a typical IHS solution is used for dissipation of unwanted heat produced by the components 103 and 104. This typical IHS solution includes a typical IHS lid 102, a first thermal interface material layer (TIM-1 layer) 105 on the component 104, and a TIM-1 layer 106 on the component 103. Sidewall regions of the typical IHS lid 102 are attached to the substrate 101 using a sealant (not shown), such that the typical IHS lid 102 is over the components 103 and 104. The TIM-1 layers 105 and 106 couple the components 104 and 103, respectively, to a central region of the typical IHS lid 102 thermally and/or mechanically.
The components 103 and 104 have varying z-heights from each other, which are collectively referred to as a height variation. Specifically, this height variation occurs because the component 104 has a larger z-height than the component 103. This height variation can include a natural height variation inherent in the manufacturing processes used to create components 103 and 104. This natural height variation can occur regardless of whether the manufacturing process used to manufacture the component 103 is the same as or different from the manufacturing process used to manufacture the component 104. Another contributor to the height variation affecting the components 103 and 104 can result from attachment mechanisms or techniques used to attach components 103 and 104 to the substrate 101. For example, if the component 103 represents a die mounted on a substrate 101 via a ball grid array (BGA) assembly (not shown), while the component 104 represents a die directly attached to substrate 101, then there can be some differences between the z-height of the components 103 and the component 104.
In addition to their heat dissipation functions, the TIM-1 layer 105 and TIM-1 layer 106 are used to compensate for this height variation. As shown in FIG. 1A, TIM-1 layer 106 is thicker than TIM-1 layer 105 to compensate for the component height difference. Compensating for the height variation affecting the components 103 and 104 occurs at the expense of increasing the z-height or bond line thickness (BLT) of the TIM-1 layers 106 and 105. Thicker BLTs of the TIM-1 layers 106 and 105, however, reduce the cooling capabilities of the TIM-1 layers 106 and 105, which in turn leads to higher chip junction temperature (Tj), limited bandwidth, frequency, greater power leakage, and the like. Additionally, absorption of the height variation by the TIM-1 layers 105 and 106 can limit choices of TIM-1 materials used for forming the TIM-1 layers 105 and 106.
Currently, an architectural IHS solution in the form of a typical three-dimensional IHS solution (typical 3D IHS solution) can avoid increasing the BLTs of the TIM-1 layers. Nevertheless, this typical 3D IHS solution fails to remedy the shortcomings of the typical IHS solution described above in connection with FIG. 1A.
FIG. 1B is a cross-sectional view of a typical MCP 150 having a typical 3D IHS solution for dissipating heat produced by the components 123 and 124. This typical 3D IHS solution includes a typical IHS lid 122, a TIM-1 layer 126 on the component 123, a TIM-1 layer 125 on the component 124, a copper (Cu) foil 127 on the TIM-1 layer 126, a Cu foil 131 on the TIM-1 layer 125, an intermediate thermal interface material layer (TIM-1A layer) 129 on the Cu foil 127, and a TIM-1A layer 133 on the Cu foil 131. In FIG. 1B, the Cu foils 127 and 131 are coupled to the typical IHS lid 122 using TIM-1A layers 129 and 133, respectively. Each respective combination of a Cu foil and a TIM-1A layer acts as an individual IHS solution for its respective component. The BLT of the TIM-1 layer 126 is substantially equal to the BLT of the TIM-1 layer 125. Moreover, the z-height of the Cu foil 127 is substantially equal to the z-height of the Cu foil 131. Consequently, the height variation affecting the components 123 and 124 is absorbed by the TIM-1A layers 129 and 133, respectively. As shown in FIG. 1B, the BLT of the TIM-1A layer 129 is larger than the BLT of the TIM-1A layer 133. Thus, the height variation affecting the components 123 and 124 is transferred from the TIM-1 layers 126 and 125 to the TIM-1A layers 129 and 133, respectively. Increases in the BLTs of the TIM-1A layers 129 and 133 result in reductions to their cooling capabilities. Consequently, the typical 3D IHS solution merely transfers the problem associated with BLTs of the TIM-1 layers to the BLTs of the TIM-1A layers.
Furthermore, the Cu foils 127 and 131 generally need to be several times larger in the x-y dimensions than the components 123 and 124. Thus, the typical 3D IHS solution is limited because it needs keep-out zones with large x-y dimensions to dissipate unwanted heat.